Such epicyclic roller gears with a rolling element are known. Above all high transmission ratios can thereby be provided. A drawback in this connection is however that the projections of the rolling element do not have any restraint with respect to the internal profile of the rings, but additional measures have to be taken in order that no backlash or freewheeling occurs within the gear, for instance during reversal of load. A zero-backlash power transmission cannot be attained. The endeavour is therefore made to eliminate these drawbacks by so-called biased gearwheels. However the production costs are thereby increased and the power transmission is affected.
It is furthermore known to produce zero backlash by elastic cages or flexible materials of the component parts, through which however the transmissible forces are limited and higher friction occurs, reducing the efficiency.
The object underlying the invention is therefore to provide a gear of the kind mentioned at the outset, permitting high reduction ratios to be achieved, but at the same time attaining a high efficiency and compulsory zero backlash.